Ecuador sent soldiers and police on Thursday to an isolated jungle area after a policeman was killed and several security officials injured in a violent protest against a Chinese copper exploration project amid conflicts between mining companies and indigenous communities.

Ecuador's president, Rafael Correa, declared a 30-day state of emergency in Morona Santiago province, home to the Panantza-San Carlos exploration project operated by the ExplorCobres company. His government said "illegally armed groups" protested against the project on Wednesday.

"Violent people want to take over the mining camp," Correa said on Twitter. "We have one dead police officer and several others injured. Criminals!"

Local media reported that the indigenous Shuar group, which accuses authorities of generating violence by kicking them out of their ancestral home to make way for mining developments, staged the protest.

The head of Ecuador's larger indigenous association, CONAIE, called on the church to mediate the conflict.

"These are no invaders, these are communities who have lived here for hundreds of years," said Jorge Herrera.